Device to facilitate the exchange of a material layer roll in the supply compartment on the fly while maintaining constant tension in the material layer

Abstract

An apparatus for unwinding and/or supplying material layers includes a rotatable driving mechanism coupled with a primary reel operable as a drive and a brake. A control unit is connected with the driving mechanism, and includes a rotational speed regulator and a tension regulator. The rotational speed regulator controls a rotational speed of the driving mechanism. The tension regulator maintains a tension in a primary material layer of a primary reel and a secondary material layer of a secondary reel. The rotational speed regulator controls the driving mechanism as a drive such that the primary reel has a rotational speed n B resulting in a tangential speed of the primary reel which is faster than the process speed of the unwinding secondary material layer. The rotational speed regulator also controls the driving mechanism as a brake such that the rotational speed is decreased from a rotational speed n B down to a synchronized rotational speed n synch , resulting in a tangential speed of the primary reel which is approximately the same as the process speed of the unwinding secondary material layer. The rotational speed regulator further controls the driving mechanism such that at approximately the instant in time when the primary material layer is glued to the secondary material layer, a brake force in the driving mechanism corresponds to a tension force required in the primary and secondary material layers to maintain a stretch within the material layers.

What is claimed is: 
     
       1. An apparatus for at least one of unwinding and supplying material layers, comprising: a primary reel with a primary material layer which unwinds therefrom, said primary reel being rotatable at a rotational speed with a tangential speed at a circumference thereof, said primary material layer having a leading edge;   a secondary reel with a secondary material layer which unwinds therefrom at a process speed, said secondary material layer having a trailing edge;   a mechanism for gluing on the fly the leading edge of said primary material layer with the trailing edge of said secondary material layer;   a rotatable driving mechanism coupled with said primary reel, said driving mechanism being operable as a drive and a brake; and   a control unit connected with said driving mechanism, said control unit including a rotational speed regulator and a tension regulator, said rotational speed regulator controlling a rotational speed of said driving mechanism, said tension regulator maintaining a tension in the material layer after said primary material layer and said secondary material layer are glued together;   wherein said rotational speed regulator controls said driving mechanism as a drive such that said primary reel has a rotational speed n B  resulting in a tangential speed of said primary reel which is faster than said process speed of said secondary material layer unwinding from said secondary reel;   wherein said rotational speed regulator controls said driving mechanism as a brake such that said rotational speed of said primary reel is decreased from said rotational speed n B  down to a synchronized rotational speed n synch , resulting in a tangential speed of said primary reel which is approximately the same as said process speed of said secondary material layer unwinding from said secondary reel; and   wherein said rotational speed regulator further controls said driving mechanism such that at approximately the instant in time when said primary material layer is glued to said secondary material layer, a brake force in said driving mechanism corresponds to a tension force required in said primary and secondary material layers to maintain a stretch within said primary and secondary material layers.   
     
     
       2. The apparatus of claim 1, wherein said driving mechanism comprises an electric engine operable as a motor and a generator. 
     
     
       3. The apparatus of claim 1, wherein said driving mechanism includes one of cooled drum brakes and disc brakes for slowing said tangential speed of said primary reel. 
     
     
       4. The apparatus of claim 1, wherein said driving mechanism comprises one of an electric motor and a hydraulic motor.